Cavity pump mechanism



June 30, 1964 w. J. ocoNNoR 3,139,035

CAVITY PUMP MECHANISM Filed Oct. 24, 1960 2 Sheets-Sheet 1 Fig.2.

gli? /fl 4o I #ze INVENTOR. Wolter J. O'Connor Jne 30, 1964 I W. J. OCONNOR CAVITY PUMP MECHANISM 2 Sheets-Sheet 2 Filed Oct. 24, 1960 rr!) v l W1 mow., I

AIV /l/w United States Patent O 5,139,035 QAWTY PUMP MECHANlSM Waiter d. QConnor, 4122 W. Washington Blvd., Grove City, Pa. snes oet. 24, rees, ser. rse. eases l2 Qlaims, (Cl. lilw-ll) This invention relates to cavity pump mechanisms of the Moineau-type having helically threaded rotor and stator pumping elements. More particularly, this invention pertains to such mechanism utilizing a solid nonyieldable rotor coacting with a stator having a wall of elastic material which can be dirnensionally regulated by pressure to deiine relatively closely the cavity in which such rotor worlrs. Mechanism of this invention, further, may provide for relative axial movement between rotor and stator for self-regulation of the pumping force. This application is an irl-part continuation of my copending application SN. 63l,239 tiled December 28, 1956 for Self-Regulating Pumping Mechanism, now Patent No. 2,957,427.

in pumps of the helical rotor type (see US. Patent No. 2,028,407), it has been a common problem to obtain a relatively precisely sized cavity in a stator having a wall of elastic material. Such a stator wall is usually molded and tends to change dimension, often to an unpredictable event, in the course of that operation, the difculty being multiplied in view of the variable thickness around the wall of the different portions providing the respective doublethreaded helical crests-and-roots cavity in which the single helically threaded rotor works. Moreover, it has been common to provide rotors and stators with multiple pitch overall lengths to increase the pumping head capacity of the device. This in turn has augmented the diflcuity encountered heretofore inasmuch as upon startup of the pump, fthe desired engagement between the rotor surface and the cavity wall of the stator, particularly in cavities of greater length, may tend to make the stator wall seize the rotor surface and in more extreme cases, the rotor will twist the elastic stator wall and even tear it, causing a breakdown of the device. On the other hand, if the engagement between rotor surface and stator cavity wall is not sufficient, the pumping operation is impaired.

in cavity pump mechanism of this invention, such deficiencies have been overcome and it is possible hereunder to control the dimension of a stator wall of elastic material to regulate the size of the cavity and/or 'the extent of hugging of the rotor surface by the cavity wall, as desired. Additionally, rotor and stator elements in a pump mechanism of this invention may automatically and selectively regulate the pumping force by relative axial movement between rotor and stator members, if and when desired, as more fully disclosed in my aforesaid copending application Serial No. 631,239 now Patent No. 2,957,427.

Other objects, features and advantages of this invention will be apparent from the following description and the accompanying drawings, which are illustrative only, in which FIGURE l is a view in longitudinal `section of one embodiment of a cavity pump mechanism of this invention;

FIGURE 2 is a view in longitudinal section of another "ice embodiment inclusive of a self-regulating pumping force feature;

FIGURE 3 is a view in longitudinal section of another embodiment of this invention having a pressure controlled stator longitudinally successive pressure stages;

FIGURE 4 is a view in longitudinal section of another embodiment of this invention; and

FIGURE 5 is a detail view taken along line V-V of FlGURE 4.

Referring to FIGURE l of the drawings, a pump sys- -tem 1li of this invention is illustrated showing a prime mover 1i in the form of an electric motor which when energized drives a drive shaft l2 through a flexible coupling 13. Shaft l2 extends through and is held against axial movement by a thrust bearing 14 in alignment with an inlet housing l5 of a cavity pump mechanism 16. A stuiling box i7 provides suitable bushing around the inner end of shaft l2 :to prevent outward leakage at that point.

Shaft 12 is counterbored at 1S for pivotal connection to a connecting rod 19 by means of a pivot pin 2.0. The outer end of the connecting rod is pivotally connected to a recess 2l in a rotor 22 by a pivot pin 23 at right angles to pivot pin 2li so that universal action flexibility is obtainable during the rotation of rotor 22.

Pump mechanism 16 is provided with a cylindrical metal shell 24 to which is atiixed by adhesive or vulcanization a stator wall 25 of molded or otherwise shaped elastic material, such as rubber or a suitable plastic. The center of stator 25 is hollow at 26 defining a cavity comprising a double lead helix for progressive engagement normally with a helical surface 27 of the single helical male thread of rotor 22. The rotor surface at least is normally made `of an unyieldable material having other suitable properties such as being resistant to corrosion where corrosive materials may have to be pumped.

Cavity 26 is entered through the interior of housing l5 down which material flows in the direction 0f arrow 2e while undergoing pumping. Such material, which may be fluid or fluid and solid, is discharged through outlet 29 in outlet housing 3d at higher pressure, exiting through outlet pipe 3l in the direction of arrow .32. An inlet pipe 33 connected to housing 15 is provided with a valve tap 34 leading to a pressure supply pipe 35. Similarly, outlet pipe 3l may be connected by a valved pressure tap 36 to a pressure supply pipe 37. The pressure supply pipes with suitable valves may be cross connected by a pipe 33. A centrifugal pump 39 is connected to pipe 38 by a valved delivery pipe 40, such pump 39 being supplied by a valve lluid line 4l. A pressure gauge 42 may be connected to pipe 4@ and others may be provided elsewhere in the system if desired. The respective lower ends of the pressure supply pipes 35 and 57 are connected to inlet fittings 43 and 44 which lead respectively to vertical branches 45 and 46 to cored hole passages 45a and 46a which are in axially displaced continuous helical arrangement underlying the respective cavity crests 47 and 48 of the elastic stator wall 25.

It will thus be seen that with the wall of stator 25 being elastic and distendable, appropriate pressure can be applied through ittings 43 and 44 to one end of each of the respective passages 45a and 46a which will relatively precisely shape the dimension of cavity Z6 relative to the rotor 22 for correct pressure engagement between the rotor and stator elements for the most eifective pumping operation. That pressure may be supplied by the pressure in the respective pipes 33 and 31 through taps 34 and 36, or the valves in those taps may be shut off and the pressure supplied to the respective pipes 35 and 37 for that purpose by the opening of the valves at the ends of pipe 38 and of the valve in pipe 40, when pump 39 is operated at the desired rate. Moreover, if upon start-up of the system 10, it is desired to back off on the engagement pressure in pump mechanism 16 between the stator and rotor, the pressure supplied through the pipes 35 and 37 can be reduced, and/or subsequently increased as the rotor 22 comes up to operating speed when it can cope effectively with a greater engagement or hugging force exerted upon its surface 27 by the cavity wall surface in the course of a pumping operation.

In the pump mechanism embodiment of FIGURE 2, the drive members have been omitted for the simplification of the representation, such drive being effected by the revolution of drive shaft 50 in an appropriate direction by a suitable prime mover. In that FIGURE 2 embodiment, a rotor 51 has an envelope generally in the form of a frustum of a cone with the portion of lesser diameter toward outlet 52 in discharge housing 53. The envelope of the surface of cavity 54 is correspondingly tapered toward the discharge end and axial displacement or movement of rotor 51 relative to the elastic stator wall 55 is provided for by a spring 56 retained in a central bore 60 in rotor 51 between retainer nuts 57 and a cap 58 pivotally connected to shaft 50. Cap 58 is provided with a longitudinal key to ride in a splineway 59 in bore 60 so that rotation of shaft 50 correspondingly rotates rotor 51 for a pumping operation. Material for pumping passes through an inlet housing 61 into the inlet end of cavity 54. The rotor and stator elements in FIGURE 2 may be made of material in the manner of the rotor and stator respectively of the FIGURE l embodiment. Hence, as the pump mechanism of FIGURE 2 operates, the pumping force is automatically self-regulated in accordance with the predetermined force setting of spring 56 which when it tends to become exceeded will move rotor 51 rearwardly as illustrated in FIGURE 2 out of transverse alignment with cavity 54 to ease up on the pumping force until the imbalance disappears, or the higher pressure in outlet 52 drops due to conditions enough to allow spring 56 to return rotor 51 to full transverse alignment with stator 55.

Apart from such self-regulating feature of the FIG- URE 2 embodiment, stator 55 is also provided with helical passages 62 and 63 corresponding to and underlying the respective double thread helical crests of cavity 54. Such passages may have threaded therethrough in each case a flexible perforated metal tube 64 or to a flexible elastic tube, which may if desired be vulcanized to the walls of such passages, if one is inserted between such metal tube 64 and the Walls of the respective passages 62 and 63. The passage 62 terminates at its respective ends in pressure fittings 65 while fittings 66 are xed to the respective ends of passage 63. Fluid under predetermined pressure is circulated through each helical passage in the stator 55 in either direction as desired, but preferably countercurrent with the inlets for the passages 62 and 63 is at the discharge end of rotor 51 where the pressure is greater in the pumping passage and outlet 52. In such countercurrency, the pressure regulating fluid would enter and leave as shown by the arrows in FIGURE 2. Again, during operation of the mechanism of FIGURE 2, the pressure in the passages 62 and 63 can be regulated as desired in the course of the operation either to accommodate a change in the speed of the rotor 51, or a change in pressure in the material being pumped.

FIGURE 3 illustrates a stator embodiment 100 of this invention in longitudinal section which has an elastic stator wall 101 defining a pump cavity 102 which coacts with a rotor 103 as hereinbefore described. The stator wall 101 is surrounded by a cylindrical metal shell 104 to which it is suitably aixed where the outside of the 4 stator engages the inside of the Wall except along the helical paths 105, 106, 107 and 108, each of such paths being formed during the shaping of the wall 101, or representing the use of some masking or other agent which will not bond to the shell 104 during the afiixation of stator 101 thereto. The result is that the paths 105 to 10S, inclusive and respectively, provide expandable and contractible helical passages for the regulation of the dimensions of cavity 102 and thereby the engagement force exerted by the stator wall 101 against rotor 102 as determined by the pressure of the fluid supply to the respective paths or passages through suitable pressure ttings respectively connected to tapped openings 109, 110, 111 and 112 into the passages through shell 104. It will be noted that each of the path passages terminates at its respective ends which in the case of passage 105 are marked 113. Hence in the FIGURE 3 embodiment, selective pressures can be applied to each of the passages for selective control of the wall portion of the stator through which such passage passes and that selectivity in the case of the FIGURE 3 embodiment is also exertable to provide separate axially successive pressure stages. For example, a selected pressure applied to taps 109 and 110 will produce a predetermined effect for the righthand side of the pumping mechanism illustrated in FIG- URE 3, while a different selected pressure applied to the taps 111 and 112 will produce a different predetermined effect in the stator wall on the left-hand side of that embodiment. Moreover, since the ends of each passage are closed, the pressure exerted in each passage will be What can be termed a static pressure, as distinguished from the kinetic circulation pressure supplied in the case of each stator wall passage shown in FIGURE 2, both types of pressure application, howeven'being utilizable for the achievement of the objects of this invention. The pressure fittings used with the taps 109 to 112 may, if desired, be in the form of Alemite or grease gun fittings for grease or other pressure uid injection, which may be intermittently renewed, used to provide the desired respective passage pressure. It will be noted further that in the FIGURE 3 embodiment, as the passages in each half progress from right to left, that is for that embodiment from lower to higher pressure, thecross sectional area of the passages increases somewhat rather uniformly to provide a corresponding increase in engagement force between stator and rotor in moving therealong toward the discharge higher pressure end.

A further stator embodiment 200 is illustrated in FIG- URE 4. It is in longitudinal section and coacts with a rotatable rotor 201. The stator proper is provided with a tubular metal shell 202 to which the outside of elastic stator wall 203 is afiixed as hereinbefore described. Stator wall 203 may be shaped in two steps, the outer portion of the stator Wall 203 being shaped with or without a groove to receive respective flattened inflatable tubes 204 and 205 for the respective helical crests of the two helical female threads defining a pumping cavity 206. The cavity Wall proper of the stator 203 may be a thinner elastic layer 207 vulcanized to the inside of the main wall portion and covering the tubes 204 and 205.

In the embodiment of FIGURE 4, pressure fittings 208 and 209 respectively conduct fluid at the desired pressure to the interior of the inflatable tubes 204 and 205 which swell upon an increase in such pressure or contract upon a diminution of such pressures. As shown, the other ends of the tubes 204 and 205 may either be closed for a static pressure control of the stator 203 inclusive of layer 207, or they may open out through other pressure fittings at the other ends of such stator passages for the achievement of the aims and accomplishments of this invention.`

In the detail showing of FIGURE 5, a pressure fitting 208 comprises a cylindrical sleeve 210 with a flanged head 211 which coacts with a ferrule 212 to pinch the circular edge 213 of an opening 214 in tube 204 immediately beneath tap 208 when nut 215 is tightened against shell 202.

The parts of the iitting other than the nut are assembled with the tube and outer part of stator wall before such outer part of stator wall is inserted in place and this is one of many ways in which such inflatable stator walls can be constructed.

Various modifications may be made in the illustrated embodiments hereinbefore described and other embodiments provided without departing from the spirit of my invention or the scope of the appended claims.

I claim:

l. In a self-regulating pumping mechanism, apparatus comprising, in combination, a tubular shell, a stator having double female helical thread portions forming the interior surface of a rotor opening therethrough, said stator being made of resilient material and having its exterior substantially surrounded and engaged by said shell, a rotor having an outer surface comprising a single male helical thread with a lead one-half that of the lead of a helix of said stator, the envelope of said rotor being substantially a frustum of a cone with its wider portion toward the inlet side of said pumping mechanism, said rotor opening having a corresponding taper, means for adjustably moving said rotor axially relative to said stator toward the narrower end of said stator to take up wear occurring between said rotor and stator, a helical passage in said stator adjacent the thread crests around the interior surface thereof, a ilexible tube in said passage vulcanized thereto, a perforated metal tube in said flexible tube, pressure iluid connections to the interior of said flexible tube for fluid pressure to provide at least one relative contact force between said rotor and stator in the course of operation, a cylindrical bore in said rotor, a cap in said bore and associated with said first-named means, means for moving said cap axially but not rotatably relative to said bore and rotor, a spring retainer in said bore spaced from said cap, a spring extending between said cap and said retainer, and a drive member universally connected to said cap, whereby low torque starting may be provided and operating pressures in the discharge from said pump casing greater than the force exerted in accordance with the character of said spring will axially displace said rotor in a direction away from said stator.

2. In a self-regulating pumping mechanism, apparatus comprising, in combination, a tubular shell, a stator of resilient material having a rotor opening defined by female helical thread portions, a helically threaded rotor, a plurality of helically threaded passages in said stator around and spaced outwardly from the surface of said rotor opening, said stator further being substantially surrounded and engaged by said shell, said rotor having one less helical thread than said stator, independent pressure fluid connections to the interior of said stator to cooperate with said passages for iluid pressure to exert at least one selected contact force between said rotor and stator in the course of operation, means operatively connected to said rotor for adjustably moving said rotor axially relative to said stator to provide a pressure relief, and a drive member ilexibly connected to said rotor.

3. In a self-regulating pumping mechanism for fluent material, apparatus comprising, in combination, a tubular shell, a stator member iixed in position along its length, said stator member having helically threaded interior surface portions forming a rotor member opening therethrough, said stator member further being substantially surrounded and engaged by said shell, a rotor member to cooperate with said stator member, said rotor member being helically threaded with one less helical thread than said stator member to cooperate with said interior surface of said stator member, said stator member being made of a resilient material, means for moving said members axially relative to one another, a passage in said stator member spaced outwardly of and around said interior surface for substantially the entire length of said stator member, said passage being out of communication with said rotor member opening, a pressure iluid connection in communication with the interior of said passage for uid pressure adapted to control by variation of pressure therein the relative Contact force between said member in the course of operation, said connection including means to etfect said control independently of the pressure of the uent material pumped by said pumping mechanism, means operatively connected to said rotor member for normally maintaining said rotor member within said stator member to a predetermined extent, and yielding means for relatively moving said members axially apart to regulate to a predetermined maximum the pumping force developed between said members by the relative axial rotation therebetween.

4. In a cavity pump mechanism of a helical rotor type, a tubular shell, a stator having an elastic Wall iixed in position along its length to said shell and dening an elongated double helical female threaded cavity extending therethrough, a single helix male thread rotor having a nonwith said stator, said stator wall having double thread crests and a continuous helical passage through said wall yieldable surface adapted to rotate in said cavity and coact spaced transversely outwardly of each crest, said passage being expandable and contractible in accordance with the pressure within said passage, and means for applying pressure to said passage, whereby a predetermined engagement force relation between said stator and rotor is producible.

5. In a cavity pump mechanism of a helical rotor type, a stator comprising a tubular shell and an elastic wall secured to said shell substantially along its outer axial length, said wall having an axially extending cavity comprising a double helical thread providing a crest and root surface, a single helical thread rotor of relatively hard material to rotate in said cavity and coact with said surface, helical passages formed and arranged between said shell and cavity spaced transversely outwardly of said crest portions, said passages being expandable and contractible in accordance with a selected fluid pressure applied to said passages respectively, and means for applying said selected iiuid pressure to said passages.

6. In a cavity pump mechanism of a helical rotor type, a tubular shell, a stator wall of elastic material fixed in position substantially along its length to said shell and detining an elongated helical cavity extending therethrough, a helical rotor adapted to rotate in said cavity and coact with the surface of said cavity, at least one helical passage within said wall and extending along the same spaced transversely outwardly of said cavity, said passage being expandable in accordance with a selected pressure in said passage, and means for applying pressure to said passage to vary cooperative engagement forces between said stator wall and rotor.

7. A cavity pump mechanism as set forth in claim 6, in which there are a plurality of such helical passages and at least one pressure fitting extending to the outside of said wall for each of said passages, whereby iluid may be used to provide said selected pressure for said passages respectively.

S. A cavity pump mechanism as set forth in claim 6, in which said last-named means includes pressure supply means connected to the interior of said pump mechanism to provide said selected pressure in accordance with the pressure of the substances being pumped by said pump mechanism.

9. A cavity pump mechanism as set forth in claim 6, having means for circulating a fluid at predetermined pressure through said passage to provide said selected pressure.

10. A cavity pump mechanism as set forth in claim 6, in which there are a plurality of separate and independent such helical passages, said passages being axially spaced, and means for applying different selected pressures to said axially spaced passages.

11. A method of pumping by cavity pump mechanism of a helical rotor type having a tubular shell, an elastic stator with a cavity therein having helical crest portions and a cooperating rotor to rotate in the cavity of said stator, comprising, in combination, supporting the exterior of said stator against said shell substantially along the axial length of said stator, rotating said rotor to pump a fluent substance through said cavity, forcing uid under pressure around said stator outwardly of said cavity and substantially along the entire length of said stator to change the effective thickness of said stator at least in the vicinity of crest portions thereof to regulate the engagement force between said stator and rotor, maintaining said uent substance and uid respectively out of communication with each other, and controlling said pressure of said fluid independently of the pressure of said iluent substance being pumped.

12. A method of operating a cavity pump mechanism as set forth in claim 11, comprising, changing said elTective .thickness of said stator in the course of a cycle of operation independently of the pressure of the fluent substance being pumped, whereby one selectively regulated engagement force may be provided upon start-up of said pump mechanism and a differentV selected engagement force may be provided when said pump mechanism is normally running.

References Cited in the le of this patent UNITED STATES PATENTS HTESIITED STATES PATENT OFFICE CERTIFICATE 0F CGRRECTION Patent No 3, 139,035 June 30, 1964 Walter- J, 'OConnor It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 6, line 20, strike out "yieldable surface adapted to rotate in said cavity and coact" and insert the same afi-ter "non-" in line 17, same olumn 6.,

Signed and sealed this 3rd day of November 1964.,

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Altesting Officer lCommissioner of Patents 

3. IN A SELF-REGULATING PUMPING MECHANISM FOR FLUENT MATERIAL, APPARATUS COMPRISING, IN COMBINATION, A TUBULAR SHELL, A STATOR MEMBER FIXED IN POSITION ALONG ITS LENGTH, SAID STATOR MEMBER HAVING HELICALLY THREADED INTERIOR SURFACE PORTIONS FORMING A ROTOR MEMBER OPENING THERETHROUGH, SAID STATOR MEMBER FURTHER BEING SUBSTANTIALLY SURROUNDED AND ENGAGED BY SAID SHELL, A ROTOR MEMBER TO COOPERATE WITH SAID STATOR MEMBER, SAID ROTOR MEMBER BEING HELICALLY THREADED WITH ONE LESS HELICAL THREAD THAN SAID STATOR MEMBER TO COOPERATE WITH SAID INTERIOR SURFACE OF SAID STATOR MEMBER, SAID STATOR MEMBER BEING MADE OF A RESILIENT MATERIAL, MEANS FOR MOVING SAID MEMBERS AXIALLY RELATIVE TO ONE ANOTHER, A PASSAGE IN SAID STATOR MEMBER SPACED OUTWARDLY OF AND AROUND SAID INTERIOR SURFACE FOR SUBSTANTIALLY THE ENTIRE LENGTH OF SAID STATOR MEMBER, SAID PASSAGE BEING OUT OF COMMUNICATION WITH SAID ROTOR MEMBER OPENING, A PRESSURE FLUID CONNECTION IN COMMUNICATION WITH THE INTERIOR OF SAID PASSAGE FOR FLUID PRESSURE ADAPTED TO CONTROL BY VARIATION OF PRESSURE THEREIN THE RELATIVE CONTACT FORCE BETWEEN SAID MEMBER IN THE COURSE OF OPERATION, SAID CONNECTION INCLUDING MEANS TO EFFECT SAID CONTROL INDEPENDENTLY OF THE PRESSURE OF THE FLUENT MATERIAL PUMPED BY SAID PUMPING MECHANISM, MEANS OPERATIVELY CONNECTED TO SAID ROTOR MEMBER FOR NORMALLY MAINTAINING SAID ROTOR MEMBER WITHIN SAID STATOR MEMBER TO A PREDETERMINED EXTENT, AND YIELDING MEANS FOR RELATIVELY MOVING SAID MEMBERS AXIALLY APART TO REGULATE TO A PREDETERMINED MAXIMUM THE PUMPING FORCE DEVELOPED BETWEEN SAID MEMBERS BY THE RELATIVE AXIAL ROTATION THEREBETWEEN. 